Coil spring prosthetic foot

Abstract

A prosthetic foot formed by one continuous coil spring which has a foot center coil section, a heel extension section, and a forefoot extension section. Lateral and medial and torsional movement are accommodated. Energy is absorbed and stored by the prosthetic foot during heel strike in the gait cycle, energy is transferred to the forefoot extension section during foot roll-forward to toe-off in the gait cycle, and energy is released to provide a propelling force on the prosthetic foot at toe-off in the gait cycle. An apparatus allowing the wearer of the prosthetic foot to feel by physical sensation forces being applied to the prosthetic foot is included in one embodiment.

I claim: 
     
       1. A foot comprising: (a) a foot center coil section having a top and a bottom,   (b) a heel extension section extending in a first direction from the bottom of said foot center coil section,   (c) a forefoot extension section extending in a second direction from the bottom of said foot center coil section,   (d) means for absorbing and storing energy when vertical force is applied to the foot,   (f) means for adjusting spring stiffness and arch height; and   (e) a receptacle to accommodate said means for adjusting spring stiffness and arch height, wherein said receptacle is formed by the interior surface of said foot center coil section;   wherein said foot center coil section, said heel extension section, and said forefoot extension section constitute a coil spring to form the foot;   wherein said foot center coil section is adapted to serve as the unitary center of the coil spring in absorbing, storing and releasing energy;   wherein said energy absorbing and storing means comprises an arch; and   wherein said means for adjusting spring stiffness and arch height is installable in said receptacle.   
     
     
       2. A foot comprising: (a) a foot center coil section having a top and a bottom,   (b) a heel extension section extending in a first direction from the bottom of said foot center coil section,   (c) a forefoot extension section extending in a second direction from the bottom of said foot center coil section,   (d) a shin section which extends from said foot center coil section;   (e) means for accommodating torsional movement about a longitudinal axis through said shin section;   wherein said foot center coil section comprises an anterior coil spring section and a posterior coil spring section and wherein said heel extension section extends from said anterior coil spring section and said forefoot extension section extends from said posterior coil section;   wherein said foot center coil section, heel extension section, and forefoot extension section constitute a coil spring to form the foot;   wherein said foot center coil section is adapted to serve as the unitary center of the coil spring in absorbing, storing and releasing energy;   wherein said torsional movement means comprises a plurality of torsional beams; and   wherein said torsional beams are generally configured as triangles in longitudinal cross section with two generally straight sides and one generally curved side.   
     
     
       3. A foot comprising: (a) a foot center coil section having a top and a bottom,   (b) a heel extension section extending in a first direction from the bottom of said foot center coil section,   (c) a forefoot extension section extending in a second direction from the bottom of said foot center coil section,   (d) a shin section which extends from said foot center coil section;   (e) means for accommodating torsional movement about a longitudinal axis through said shin section;   wherein said foot center coil section comprises an anterior coil spring section and a posterior coil spring section and wherein said heel extension section extends from said anterior coil spring section and said forefoot extension section extends from said posterior coil section;   wherein said foot center coil section, heel extension section, and forefoot extension section constitute a coil spring to form the foot;   wherein said foot center coil section is adapted to serve as the unitary center of the coil spring in absorbing, storing and releasing energy;   wherein said torsional movement means comprises a plurality of torsional beams; and   wherein said torsional beams extend from said anterior coil spring section and from said posterior coil spring section;   
     
     
       4. A foot comprising: (a) a foot center coil section having a top and a bottom,   (b) a heel extension section extending in a first direction from the bottom of said foot center coil section,   (c) a forefoot extension section extending in a second direction from the bottom of said foot center coil section; and   (d) means for absorbing and storing energy when vertical force is applied to the foot;   wherein said foot center coil section, heel extension section, and forefoot extension section constitute a coil spring to form the foot;   wherein said heel extension section is adapted to absorb and store energy at heel strike during the gait cycle;   wherein said foot center coil section is adapted to transfer energy stored during heel strike to another portion of the foot during foot roll-forward of the gait cycle;   wherein said forefoot extension section is adapted to release stored energy at toe-off during the gait cycle to provide a gait-enhancing propelling force on the foot;   wherein said energy absorbing means comprises:   (i) a shin section having a longitudinal axis, said shin section being connected to said foot center coil section, said shin section comprising a plurality of torsional beams;   wherein said torsional beams bow outward to absorb and store energy as vertical force is applied to the foot; and   wherein said shin section experiences a vertical displacement along its longitudinal axis as a result of bowing of said torsional beams.   
     
     
       5. A foot as recited in claim 4 wherein said energy absorbing means further comprises: (ii) a center rod along the longitudinal axis of said shin section about which said torsional beams have the ability to bow.   
     
     
       6. A foot as recited in claim 5 wherein said energy absorbing means further comprises: (iii) means for limiting vertical displacement of said shin section.   
     
     
       7. A foot as recited in claim 6 wherein said means for limiting vertical displacement comprises a clamp.